A Welsh government spokesman said: "Despite increased demand on the NHS in Wales, the health service is treating more patients, with the vast majority being seen within target times.

"Over the last five years, referrals to hospital-based services have increased by around 20% - from 1.07 million in 2012/13 to 1.27 million in 2015/16.

"Increases in individual specialities are even higher, with orthopaedic referrals alone up 22%.

"Despite this, latest figures show over half of patients are waiting less than 10 weeks for treatment, while there has been a 28% reduction in the number waiting over 36 weeks in March 2017 compared with the same period in 2016.

"However, we acknowledge some people are still wait too long for treatment. That's why we established the planned care programme to help NHS Wales deliver sustainable services.

"In addition, health boards have action plans in place to reduce long waits, and earlier this month, the Health Secretary announced an extra £50 million to help the NHS further improve waiting times."

But Angela Burns, Welsh Conservative Shadow Health Secretary said: "No one should have to wait more than a year for surgery, but that's becoming a painful reality for more and more NHS patients in Wales.

"That nearly three times as many patients in Wales - a country 17 times smaller than England - waited more than 52 weeks for surgery really underscores the hypocrisy of Jeremy Corbyn and his Labour party.

"He and his comrades have in the past flattered themselves with the moniker of 'a government in waiting', but here in Wales, Labour are little more than the government of waiting times, which continue to grow unabated.

"Betsi Cadwaladr health board, which went into special measures - the highest form of Welsh Government control - two years ago, has seen its year-plus waiting times go from zero to 1,202 in that time.

"The longer patients are allowed to languish on waiting lists, the more complex their needs become, and the more expensive their treatment is to minister.

"In the absence of a long-term strategy, the Welsh NHS is staring into an abyss. It's up to the Labour administration to finally get a handle on the situation or face a health service beyond repair."

Tim Havard, regional director for Wales at the Royal College of Surgeons, said that the problem could be tackled by a renewed focus on community care.

He said: "A patient's condition can also deteriorate the longer they are made to wait for treatment, meaning the eventual outcomes are not as good as they could have been.

"The Welsh health service is facing a raft of pressures, with hospital wards being filled with patients that should be treated in the community and a continued squeeze on finances.

"Improving the availability of community beds, primary care, and caring for people in their own home would significantly reduce unnecessary and prolonged hospital admissions.

"The ongoing parliamentary review of health and social care in Wales offers an opportunity to confront some of the problems causing long waits for treatments and give patients the timely access to care they require."